Introduce synonyms for empty config constructor to clarify usage

community/consistency-check-legacy/src/test/java/org/neo4j/legacy/consistency/checking/full/FullCheckIntegrationTest.java

@@ -434,7 +434,7 @@ public void shouldNotReportIndexInconsistenciesIfIndexIsFailed() throws Exceptio
             IndexRule rule = rules.next();
             IndexDescriptor descriptor = new IndexDescriptor( rule.getLabel(), rule.getPropertyKey() );
             IndexConfiguration indexConfig = IndexConfiguration.NON_UNIQUE;
-            IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+            IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
             IndexPopulator populator =
                 storeAccess.indexes().getPopulator( rule.getId(), descriptor, indexConfig, samplingConfig );
             populator.markAsFailed( "Oh noes! I was a shiny index and then I was failed" );
@@ -541,7 +541,7 @@ protected void transactionData( GraphStoreFixture.TransactionDataBuilder tx,
     public void shouldReportNodesThatAreNotIndexed() throws Exception
     {
         // given
-        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
         for ( IndexRule indexRule : loadAllIndexRules( fixture.directStoreAccess().nativeStores().getSchemaStore() ) )
         {
             IndexAccessor accessor = fixture.directStoreAccess().indexes().getOnlineAccessor(
@@ -565,7 +565,7 @@ public void shouldReportNodesWithDuplicatePropertyValueInUniqueIndex() throws Ex
     {
         // given
         IndexConfiguration indexConfig = IndexConfiguration.NON_UNIQUE;
-        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
         for ( IndexRule indexRule : loadAllIndexRules( fixture.directStoreAccess().nativeStores().getSchemaStore() ) )
         {
             IndexAccessor accessor = fixture.directStoreAccess()

community/consistency-check-legacy/src/test/java/org/neo4j/unsafe/impl/batchimport/ParallelBatchImporterTest.java

@@ -149,7 +149,7 @@ public void shouldImportCsvData() throws Exception
         ExecutionMonitor processorAssigner = eagerRandomSaturation( config.maxNumberOfProcessors() );
         final BatchImporter inserter = new ParallelBatchImporter( directory.graphDbDir(),
                 new DefaultFileSystemAbstraction(), config, NullLogService.getInstance(),
-                processorAssigner, EMPTY, new Config() );
+                processorAssigner, EMPTY, Config.empty() );
 
         boolean successful = false;
         IdGroupDistribution groups = new IdGroupDistribution( NODE_COUNT, 5, random.random() );

community/consistency-check/src/test/java/org/neo4j/consistency/checking/full/FullCheckIntegrationTest.java

@@ -475,7 +475,7 @@ public void shouldNotReportIndexInconsistenciesIfIndexIsFailed() throws Exceptio
             IndexRule rule = rules.next();
             IndexDescriptor descriptor = new IndexDescriptor( rule.getLabel(), rule.getPropertyKey() );
             IndexConfiguration indexConfig = IndexConfiguration.NON_UNIQUE;
-            IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+            IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
             IndexPopulator populator =
                 storeAccess.indexes().getPopulator( rule.getId(), descriptor, indexConfig, samplingConfig );
             populator.markAsFailed( "Oh noes! I was a shiny index and then I was failed" );
@@ -582,7 +582,7 @@ protected void transactionData( GraphStoreFixture.TransactionDataBuilder tx,
     public void shouldReportNodesThatAreNotIndexed() throws Exception
     {
         // given
-        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
         for ( IndexRule indexRule : loadAllIndexRules( fixture.directStoreAccess().nativeStores().getSchemaStore() ) )
         {
             IndexAccessor accessor = fixture.directStoreAccess().indexes().getOnlineAccessor(
@@ -606,7 +606,7 @@ public void shouldReportNodesWithDuplicatePropertyValueInUniqueIndex() throws Ex
     {
         // given
         IndexConfiguration indexConfig = IndexConfiguration.NON_UNIQUE;
-        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( new Config() );
+        IndexSamplingConfig samplingConfig = new IndexSamplingConfig( Config.empty() );
         for ( IndexRule indexRule : loadAllIndexRules( fixture.directStoreAccess().nativeStores().getSchemaStore() ) )
         {
             IndexAccessor accessor = fixture.directStoreAccess()

community/consistency-check/src/test/java/org/neo4j/unsafe/impl/batchimport/ParallelBatchImporterTest.java

@@ -19,12 +19,6 @@
  */
 package org.neo4j.unsafe.impl.batchimport;
 
-import org.apache.commons.lang3.mutable.MutableLong;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.junit.runners.Parameterized;
-
 import java.io.File;
 import java.io.IOException;
 import java.io.PrintStream;
@@ -40,6 +34,12 @@
 import java.util.Set;
 import java.util.UUID;
 
+import org.apache.commons.lang3.mutable.MutableLong;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+
 import org.neo4j.consistency.ConsistencyCheckService;
 import org.neo4j.consistency.ConsistencyCheckService.Result;
 import org.neo4j.consistency.checking.full.ConsistencyCheckIncompleteException;
@@ -72,6 +72,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
+
 import static org.neo4j.helpers.collection.IteratorUtil.asSet;
 import static org.neo4j.helpers.collection.MapUtil.stringMap;
 import static org.neo4j.unsafe.impl.batchimport.AdditionalInitialIds.EMPTY;
@@ -151,7 +152,7 @@ public void shouldImportCsvData() throws Exception
         ExecutionMonitor processorAssigner = eagerRandomSaturation( config.maxNumberOfProcessors() );
         final BatchImporter inserter = new ParallelBatchImporter( directory.graphDbDir(),
                 new DefaultFileSystemAbstraction(), config, NullLogService.getInstance(),
-                processorAssigner, EMPTY, new Config() );
+                processorAssigner, EMPTY, Config.empty() );
 
         boolean successful = false;
         IdGroupDistribution groups = new IdGroupDistribution( NODE_COUNT, 5, random.random() );

community/cypher/cypher/src/test/scala/org/neo4j/cypher/internal/compiler/v3_0/LazyTest.scala

@@ -196,7 +196,7 @@ class LazyTest extends ExecutionEngineFunSuite {
     val dependencies = mock[DependencyResolver]
     val bridge = mock[ThreadToStatementContextBridge]
     val monitors = new org.neo4j.kernel.monitoring.Monitors()
-    val config = new Config()
+    val config = Config.empty()
 
     val fakeDataStatement = mock[OperationsFacade]
     val fakeReadStatement = mock[ReadOperations]

community/import-tool/src/main/java/org/neo4j/tooling/ImportTool.java

@@ -74,6 +74,7 @@
 import static org.neo4j.helpers.Exceptions.launderedException;
 import static org.neo4j.helpers.Format.bytes;
 import static org.neo4j.helpers.Strings.TAB;
+import static org.neo4j.kernel.configuration.Config.defaults;
 import static org.neo4j.kernel.impl.util.Converters.withDefault;
 import static org.neo4j.unsafe.impl.batchimport.Configuration.BAD_FILE_NAME;
 import static org.neo4j.unsafe.impl.batchimport.input.Collectors.badCollector;
@@ -430,7 +431,7 @@ public static void main( String[] incomingArguments, boolean defaultSettingsSuit
 
     private static Config loadDbConfig( File file ) throws IOException
     {
-        return file != null && file.exists() ? new Config( MapUtil.load( file ) ) : new Config();
+        return file != null && file.exists() ? new Config( MapUtil.load( file ) ) : Config.defaults();
     }
 
     private static void printOverview( File storeDir, Collection<Option<File[]>> nodesFiles,

community/import-tool/src/test/java/org/neo4j/tooling/QuickImport.java

@@ -86,7 +86,7 @@ public static void main( String[] arguments ) throws IOException
                 COMMAS, nodeCount, relationshipCount, new Groups(), idType, labelCount, relationshipTypeCount,
                 silentBadCollector( 0 ));
         BatchImporter importer = new ParallelBatchImporter( dir, DEFAULT,
-                new SimpleLogService( sysoutLogProvider, sysoutLogProvider ), defaultVisible(), new Config() );
+                new SimpleLogService( sysoutLogProvider, sysoutLogProvider ), defaultVisible(), Config.defaults() );
         importer.doImport( input );
     }
 

community/kernel/src/main/java/org/neo4j/kernel/configuration/Config.java

@@ -58,7 +58,7 @@
 public class Config implements DiagnosticsProvider, Configuration
 {
     private final List<ConfigurationChangeListener> listeners = new CopyOnWriteArrayList<>();
-    private final Map<String, String> params = new ConcurrentHashMap<>(  );
+    private final Map<String, String> params = new ConcurrentHashMap<>();
     private final ConfigValues settingsFunction;
 
     // Messages to this log get replayed into a real logger once logging has been
@@ -70,6 +70,16 @@ public class Config implements DiagnosticsProvider, Configuration
     private ConfigurationMigrator migrator;
     private ConfigurationValidator validator;
 
+    public static Config empty()
+    {
+        return new Config();
+    }
+
+    public static Config defaults()
+    {
+        return new Config();
+    }
+
     public Config()
     {
         this( new HashMap<>(), Collections.<Class<?>>emptyList() );
@@ -94,6 +104,7 @@ public Config( Map<String, String> inputParams, Iterable<Class<?>> settingsClass
 
     /**
      * Returns a copy of this config with the given modifications.
+     *
      * @return a new modified config, leaves this config unchanged.
      */
     public Config with( Map<String, String> additionalConfig )
@@ -125,19 +136,20 @@ public <T> T get( Setting<T> setting )
      * the raw setting data, meaning it can provide functionality that cross multiple settings
      * and other more advanced use cases.
      */
-    public <T> T view( Function<ConfigValues,T> projection )
+    public <T> T view( Function<ConfigValues, T> projection )
     {
         return projection.apply( settingsFunction );
     }
 
     /**
      * Augment the existing config with new settings, overriding any conflicting settings, but keeping all old
      * non-overlapping ones.
+     *
      * @param changes settings to add and override
      */
-    public Config augment( Map<String,String> changes )
+    public Config augment( Map<String, String> changes )
     {
-        Map<String,String> params = getParams();
+        Map<String, String> params = getParams();
         params.putAll( changes );
         applyChanges( params );
         return this;
@@ -204,7 +216,9 @@ public synchronized Config applyChanges( Map<String, String> newConfiguration )
         return this;
     }
 
-    /** Add more settings classes. */
+    /**
+     * Add more settings classes.
+     */
     public Config registerSettingsClasses( Iterable<Class<?>> settingsClasses )
     {
         this.settingsClasses = Iterables.concat( settingsClasses, this.settingsClasses );
@@ -281,24 +295,27 @@ public String toString()
     }
 
     /**
-     * This mechanism can be used as an argument to {@link #view(Function)} to view a set of config options that share a common base config key as a group.
-     * This specific version handles multiple groups, so the common base key should be followed by a number denoting the group, followed by the group config
+     * This mechanism can be used as an argument to {@link #view(Function)} to view a set of config options that
+     * share a common base config key as a group.
+     * This specific version handles multiple groups, so the common base key should be followed by a number denoting
+     * the group, followed by the group config
      * values, eg:
-     *
+     * <p>
      * {@code <base name>.<group key>.<config key>}
-     *
-     * The config of each group can then be accessed as if the {@code config key} in the pattern above was the entire config key. For example, given the
+     * <p>
+     * The config of each group can then be accessed as if the {@code config key} in the pattern above was the entire
+     * config key. For example, given the
      * following configuration:
-     *
+     * <p>
      * <pre>
      *     dbms.books.0.name=Hansel & Gretel
      *     dbms.books.0.author=JJ Abrams
      *     dbms.books.1.name=NKJV
      *     dbms.books.1.author=Jesus
      * </pre>
-     *
+     * <p>
      * We can then access these config values as groups:
-     *
+     * <p>
      * <pre>
      * {@code
      *     Setting<String> bookName = setting("name", STRING); // note that the key here is only 'name'
@@ -309,27 +326,28 @@ public String toString()
      * }
      * </pre>
      *
-     * @param baseName the base name for the groups, this will be the first part of the config key, followed by a grouping number, followed by the group
+     * @param baseName the base name for the groups, this will be the first part of the config key, followed by a
+     *                 grouping number, followed by the group
      *                 config options
      * @return a list of grouped config options
      */
-    public static Function<ConfigValues,List<Configuration>> groups( String baseName )
+    public static Function<ConfigValues, List<Configuration>> groups( String baseName )
     {
         Pattern pattern = Pattern.compile( Pattern.quote( baseName ) + "\\.(\\d+)\\.(.+)" );
 
         return ( values ) -> {
-            Map<String,Map<String,String>> groups = new HashMap<>();
-            for ( Pair<String,String> entry : values.rawConfiguration() )
+            Map<String, Map<String, String>> groups = new HashMap<>();
+            for ( Pair<String, String> entry : values.rawConfiguration() )
             {
                 Matcher matcher = pattern.matcher( entry.first() );
 
-                if( matcher.matches() )
+                if ( matcher.matches() )
                 {
                     String index = matcher.group( 1 );
                     String configName = matcher.group( 2 );
                     String value = entry.other();
 
-                    Map<String,String> groupConfig = groups.get( index );
+                    Map<String, String> groupConfig = groups.get( index );
                     if ( groupConfig == null )
                     {
                         groupConfig = new HashMap<>();
@@ -339,7 +357,7 @@ public static Function<ConfigValues,List<Configuration>> groups( String baseName
                 }
             }
 
-            Function<Map<String,String>,Configuration> mapper = m -> new Configuration()
+            Function<Map<String, String>, Configuration> mapper = m -> new Configuration()
             {
                 @Override
                 public <T> T get( Setting<T> setting )

community/kernel/src/main/java/org/neo4j/kernel/impl/pagecache/StandalonePageCacheFactory.java

@@ -43,7 +43,7 @@ private StandalonePageCacheFactory()
 
     public static PageCache createPageCache( FileSystemAbstraction fileSystem )
     {
-        return createPageCache( fileSystem, new Config() );
+        return createPageCache( fileSystem, Config.defaults() );
     }
 
     public static PageCache createPageCache(

community/kernel/src/main/java/org/neo4j/kernel/impl/store/StoreAccess.java

@@ -79,7 +79,7 @@ public StoreAccess( PageCache pageCache, File storeDir )
 
     public StoreAccess( FileSystemAbstraction fileSystem, PageCache pageCache, File storeDir )
     {
-        this( fileSystem, pageCache, storeDir, new Config() );
+        this( fileSystem, pageCache, storeDir, Config.defaults() );
     }
 
     private StoreAccess( FileSystemAbstraction fileSystem, PageCache pageCache, File storeDir, Config config )

community/kernel/src/main/java/org/neo4j/kernel/impl/store/StoreFactory.java

@@ -76,7 +76,7 @@ public StoreFactory()
 
     public StoreFactory( FileSystemAbstraction fileSystem, File storeDir, PageCache pageCache, LogProvider logProvider )
     {
-        this( storeDir, new Config(), new DefaultIdGeneratorFactory( fileSystem ), pageCache, fileSystem,
+        this( storeDir, Config.defaults(), new DefaultIdGeneratorFactory( fileSystem ), pageCache, fileSystem,
                 logProvider );
     }
 

community/kernel/src/main/java/org/neo4j/kernel/impl/storemigration/legacystore/v21/propertydeduplication/IndexLookup.java

@@ -52,7 +52,7 @@ public IndexLookup( SchemaStore store, SchemaIndexProvider schemaIndexProvider )
         indexAccessors = new ArrayList<>();
         readerCache = new HashMap<>();
         indexRuleIndex = buildIndexRuleIndex( store );
-        samplingConfig = new IndexSamplingConfig( new Config() );
+        samplingConfig = new IndexSamplingConfig( Config.defaults() );
     }
 
     private PrimitiveIntObjectMap<List<IndexRule>> buildIndexRuleIndex( SchemaStore schemaStore )

community/kernel/src/test/java/org/neo4j/graphdb/factory/GraphDatabaseSettingsTest.java

@@ -41,7 +41,7 @@ public class GraphDatabaseSettingsTest
     @Test
     public void mustHaveReasonableDefaultPageCacheMemorySizeInBytes() throws Exception
     {
-        long bytes = new Config().get( GraphDatabaseSettings.pagecache_memory );
+        long bytes = Config.defaults().get( GraphDatabaseSettings.pagecache_memory );
         assertThat( bytes, greaterThanOrEqualTo( ByteUnit.mebiBytes( 32 ) ) );
         assertThat( bytes, lessThanOrEqualTo( ByteUnit.tebiBytes( 1 ) ) );
     }
@@ -58,7 +58,7 @@ public void pageCacheSettingMustAcceptArbitraryUserSpecifiedValue() throws Excep
     @Test( expected = InvalidSettingException.class )
     public void pageCacheSettingMustRejectOverlyConstrainedMemorySetting() throws Exception
     {
-        long pageSize = new Config().get( GraphDatabaseSettings.mapped_memory_page_size );
+        long pageSize = Config.defaults().get( GraphDatabaseSettings.mapped_memory_page_size );
         Setting<Long> setting = GraphDatabaseSettings.pagecache_memory;
         String name = setting.name();
         // We configure the page cache to have one byte less than two pages worth of memory. This must throw:

community/kernel/src/test/java/org/neo4j/kernel/api/index/IndexAccessorCompatibility.java

@@ -59,7 +59,7 @@ public IndexAccessorCompatibility( IndexProviderCompatibilityTestSuite testSuite
     public void before() throws Exception
     {
         IndexConfiguration indexConfig = IndexConfiguration.of( isUnique );
-        IndexSamplingConfig indexSamplingConfig = new IndexSamplingConfig( new Config() );
+        IndexSamplingConfig indexSamplingConfig = new IndexSamplingConfig( Config.empty() );
         IndexPopulator populator = indexProvider.getPopulator( 17, descriptor, indexConfig, indexSamplingConfig );
         populator.create();
         populator.close( true );